摘要:
Objective To investigate the effects of silica dust on the expression of Myeloid differentiation factor 88(MyD88) mRNA and tumor necrosis factor receptor-associated factor(TRAF6) mRNA of lung macrophages in rats. Methods Selecting 40 SPF-class Wistar rats with average weight (200 ±20) g randomly divided into control group and 30 d, 60 d, 120 d experimental groups with 10 rats in each group according to body weight.The experimental groups rats were injected with 1 ml of SiO2(100 mg/ml) suspension through the trachea into lung only once, then they were respectively killed after 30, 60, 120 days.The control group rats were injected with 1 ml of saline into lung, and killed after 120 days. The lungs of the rats were taken for pathological observation. Lung macrophages were extracted and counted,and their activity was detected by MTT. RT-qPCR was used to assess the relative contents of MyD88 mRNA and TRAF6 mRNA. Results Silica dust inhalation led to infiltration of lung tissue cells, thickening the alveolar wall and destruction of alveolar structure. The longer the exposure to dust, the more obvious the results were. The number of macrophages in all experimental groups and activity in the 30 d, 60 d groups were significantly higher than that in the control group(P<0.05).Among them, 30 d group had the largest number and the highest activity. Compared with the control group, the expression of MyD88 mRNA and TRAF6 mRNA of lung macrophages in rats increased in the experimental groups (P<0.05), especially in the 60 d group.Conclusion Silica dust inhalation can increase the expression of MyD88 and TRAF6 in macrophages, suggesting that silica dust can induce silicosis fibrosis by activating TLR/NF-κB signal pathway.%目的 探讨矽尘对大鼠肺巨噬细胞髓样分化因子88(MyD88)和肿瘤坏死因子受体相关因子6(TRAF6)mRNA表达的影响.方法 选择SPF级Wistar大鼠40只,平均体重(200±20) g,按体重随机分为对照组和30、60、120 d染尘组. 30、60和120 d染尘组采用非暴露式一次性染尘,经气管向大鼠肺脏注入1 ml SiO2悬浊液(100 mg/ml),分别于染尘后30、60和120 d处死;对照组肺脏注射1 ml生理盐水,120 d后处死.取各组大鼠肺脏,观察肺组织病理;提取肺巨噬细胞计数,3-(4,5-二甲基噻唑-2)-2,5-二苯基四氮唑溴盐(MTT)检测其活力,实时荧光定量PCR(RT-qPCR)法检测MyD88和TRAF6 mRNA的相对含量.结果 染尘组大鼠肺组织细胞浸润增多,肺间质增厚,肺泡结构破坏,染尘时间越长,损伤越严重;对照组肺泡结构清晰,形态正常.各染尘组大鼠肺巨噬细胞数目及30、60 d染尘组巨噬细胞相对活力明显高于对照组,差异均有统计学意义(P<0.05).与对照组比较,60和120 d染尘组大鼠肺巨噬细胞MyD88和TRAF6 mRNA的表达增高,差异均有统计学意义(P<0.05).结论 矽尘吸入可导致大鼠肺巨噬细胞MyD88、TRAF6的表达升高,可能通过激活Toll样受体/核因子κB(TLR/NF-κB)信号通路诱发矽肺纤维化.